Operating mechanism for timepieces



March 20, 1928.

N. D. HOLBROOK OPERATING MECHANISM FOR TIMEPIECES Filed Sept. 2. 1926 3714mm or mafia W Patented Mar. 20, 1928.

UNlTED STATES mama) NEWTON D. HQLBROOIK, OF THOMASTON, CONNECTICUT.

OPERATING MECHANISM FOR TIMEPIEGES.

Application filed September 2, 1926. Serial No. 133,126.

This invention relates to mechanism which is designed for driving the time train of watch and clock movements in which the source of power is electrical, and while 1t is serviceable for electric clocks generally it is particularly adapted for time pieces used on automobiles. Automobile tune pieces are subject to intensive vibration and unless the power is maintained un form the regularity of beat and accuracy of time-keeping is seriously affected, there is habihty of over-banking with the result that they fall to run correctly if they do not stop.

The object of this invention'as to provide a simple and reliable mechanism which is actuated for tensioning the main driving spring by periodical electric impulses, the intervals of which are controlled by the running of the time train, the driving mechanism being so composed and the connection so made that, although the source of power is periodic, the driving force is maintained uniform, even during the moments in which the electric impulses act for tensioning the main spring, whereby the tune train will be driven by substantially steady pressure and the liability to inaccurate timing, over-banking and stopping Wlll be eliminated.

This end is attained by providing an electromagnet, which may be composed of one,

' two or three windings, with two armatures,

a main driving armature and a supplemental circuit controlling armature, both of. which are subject to the influence of the magnet. The driving armature under the pull of the magnet tensions the tlme train driving spring, which spring as the time train runs retracts the driving armature. The supplemental armature is flexible and carries a contact which is caused to close the circuit through the magnet when the main armature is retracted to the desired degree, and is caused to open the circuit when the main armature is attracted sub stantially its full distance, the supplemental armature being actuated to an extent by p the movements of the main armature but with alost motion connection, whereby the circuit contacts are not instantly disengaged when the main armature is attracted but are held closed for a short interval by the magnetic pull upon the supplemental armature. With this arrangement the pull of the magnet is employed to tension the time tram dIlVlIlg spring and open the circuit, but at the same time the magnet pull is utilized to keep the circuit closed until the driving spring is substantially tensioned. Means are provided to definitely limit the movement of the main magnet armature and the make and break contact, and to prevent undue arcing of the contacts when the circuit is opened. The driving mechanism is connected with the time train driving arbor by positive means but which is capable of slight expansion so as to keep the connection close at the instant that the main spring is tensioned, and thus contribute in maintaining the even driving pressure on the time train.

In the accompanying drawings Fig. 1 is a view looking from the back of a driving mechanism having three magnet windings, which embodies the invention, the parts being in the position occupied when the electric circuit is open. Fig. 2 is a view looking from the front of this form of the driving mechanism. Fig. 3 is a section taken on the plane 33 on Fig. 1, of the driving mechanism showing its connection with the time train driving arbor. Fig. 4 is asection on the plane indicated by the dotted line 44 on Fig. 2. Fig. 5 is a view of the means that is attached to the driving arbor of the time train for the connection of the drivlng mechanism therewith, the parts being shown in driving position. Fig. 6 is a similar view with the parts in the positions assumed at the instant the driving spring is tensioned. Fig. 7 is a plan view of a modified construction. Fig. 8 is an end view of the modified form. this modified arrangement having only one magnet winding.

In the first form illustrated the main driving magnet has two series connected windings 1 on cores 2 fastened to the back of the plate 3. The armature 4 of this magnet is mounted so as to oscillate transversely toward and from the magnet cores, the ro tatory spindle 5 to which it is fastened being supported by a sleeve 6 that projects from the back of the plate. Fastened to-the main driving armature spindle, on the front of the plate is a rocker 7. Pivoted to the secno I with the ratchet wheel teeth by a spring 14 so as to prevent this wheel from turning backward when the driving pawl is "re tracted. The ratchet wheel has two forwardly extending pins 15 that are designed to, when the wheel is rotated by the push of the pawl, engage the fingers 16 which are attached to a disk 17 fastened to the drivmg arbor 18 of the time train. When the driving pressure is exerted on the time train these fingers close together and provide a positive driving connection, as illustrated in Fig. 5, but at the instant that the driving spring is tensioned and the driving pressure tends to relax the resilience of these fingers causesthemto spring out, as shown in Fig. 6

and thus keep them in close engagement with the pins on the ratchet wheel at all times. The end 19 of the rocker 7 is bent backward through a slot 20 in the plate and terminates in a fork 21 on the other" side of the plate. By means of these elements when the mag: nets are energized by closing the circuit the driving armature is oscillated toward the cores so as to turn the rocker and tension the driving spring and retract the pawl over the teeth of the ratchet wheel. When the circult through the magnets is opened the spring retracts the driving armature and through the pawl turns the ratchet wheel so as to drive the time train. This action is repeated as frequently as the magnets are energized and deenerglzed.

one end of the winding of a supplemental magnet 23. The other end of the supplemental magnet winding is connected with a contact 24. This supplemental or switching magnet is smaller and less powerful than the main driving magnet. The armature 25 of the supplemental magnet is mounted on a spring finger 26 of conducting material which at its free end has a contact 27 adapted to engage with the contact 24, and at the other end the finger is fastened to the plate by a stud 28. This finger is in electrical connection with a bindingscrew 29 for the attachment of one of the leads from thesource of electrical energy. Q The spring finger carrying the armature and contact passes be tween and is adapted to be engaged by the prongs of the fork 21 on the end of the section 1 9 of the rocker that is fastened to the main driving armature spindle. The space between the fork prongs is wider than the thickness of the finger'so thatthere will be a lost motion engagement between these parts, that is, so that the fork will move some distance before it engages and moves the finger.

A resistance 30 may be connected in the v neeaeac circuit around the main driving magnets, that is, from one side of the main magnet windings to the other .side of these magnet windings, for the purpose of sh unting these windings and eliminating arcing when the contacts adjacent to the supplemental magnet are disengaged and the circuit is opened.

When this arrangement of the mechanism is connectedin series with a source ofelectrical energy and the contacts at the end of the supplemental magnet and on its'spring armature are engaged, current flows through both the main and supplemental magnets and the pull of the main magnets oscillates the main driving arbor and causes it to tension the main driving spring. As-this occurs the fork releases the spring armature of the supplemental magnet. which then tends to spring out and open the circuit, but owing to the magnetism of the supplemental magnot this contact is retained in engagement.

for an instant or until the lost motion of the fork is taken up and then the fork engages the spring armature and causes it to, Jpenthe circuit. With the circuit open and the driving spring under tension the time train runs until the pawl under the pull of the driving spring has reached the desired limit of its movement. During this-movement the fork is moving back and is carrying the springarmature contact toward the fixed cont-act. When the contacts again engage and the circuit is remade the driving armature is again oscillated and the action of the parts is repeated. As stated, owing to the lost motion between the fork and the spring armature finger and the magnetic pull of the supplemental magnet, the engagement of the contacts is not instantly broken when the current is sufficiently reduced in the main magnets to permit the pull of the main driving magnet spring to retract the main driving armature. There is a slight interval of time between the action of the main driving armature and the action of the spring armature and this permits the.

driving spring to be fully tensioned before the circuit is completely broken. The pull of the supplemental magnet insures positive engagement. of the contacts, and whatever tendency there is to back lash or. resistance from the time train is eliminated by the spring fingers which connect the driven ratchet wheel with the time train driving arbor. The fork is'limited in its movement by the ends of the slot through which it passes and therefore the amount of oscillation of' the main driving magnet is' always the same, which results in a uniform tension being given to the driving spring and an exact amount ofmovement given to the ardriving spring 38 that is tensioned when the armature is attracted toward the core of the magnet. The free end of this arm is bent outward and has a slot 39.

The supplemental or circuit controlling armature 4:0 is in the shape of a spring finger which is fastened to the arm projecting from the main armature, and extends freely through the slot in the bent end of the arm. This supplemental armature is adapted to be attracted by the magnetic pull of the extension 41 from the end of the core 32. The supplemental armature carries a contact 42 which is designed to engage a fixed contact 43 on the finger H which is fastened to the end of the magnet and to which one end of the magnet winding is connected.

The action of this modified arrangement is substantially the same as that of the arrangement first described. As the time train.

runs under the pull of the driving spring the main armature is retracted until the contact on the supplemental armature attached to the main armature engages the fixed contact. This closes the circuit and the main armature is then attracted and the driving spring tensioned. The movement of the driving armature when attracted is in such a direction as to tend to disengage the contacts and open the circuit. However, owing to the lost motion connection between the walls of the slot in the end of the arm extending from the main armature, and the spring finger supplemental armature, the circuit is not instantly opened for the magnet holds the supplemental armature with the circuit contacts engaged until the lost motion is taken up and then the further movement of the main armature causes the contacts to separate and the circuit to be come broken. This, however, does not take place until the main driving spring is practically fully tensioned;

In both forms illustrated and described, whether the operating magnet is divided so as to have three windings or it has only one winding,.when the circuit is closed the same magnetic impulse which causes the main armature to tension the driving spring and open the circuit is exerted on the su pleinental armature to retain the circuit 0 osed until the lost motion between the two is taken up and the driving spring is given a substantial driving tension.

The invention claimed is:

1. A time train driving mechanism comprising a main driving magnet, a supplemental switching magnet in series therewith, a. driving armature for the main magnet, a switching armature for the supplemental magnet adapted to open and close the circuit through the magnets, a time train driving Wheel, a pawl engaging said wheel, a spring arranged to cause the pawl to drive said wheel, and means actuated by the movements of the driving armature for tensioning the driving spring and retracting the pawl, said means also adapted to engage and move said switching armature of the supplemental magnet. r

2. A time train driving mechanism comprising a main driving magnet, a supplemental switching magnet in series therewith, a driving armature for the main magnet, a switching armature for the supplemental magnet adapted to open and close the circuit through the magnets, a time train driving wheel, a pawl engaging said wheel, a spring arranged to cause the pawl to drive said wheel, and means actuated by the movements of the-driving armature for tensioning the driving spring and retracting the pawl, said means including a fork having a lost motion engagement with said switching armature of the supplemental magnet.

3. A time train driving mechanism comprising a main driving magnet, a supplemental switching magnet in series therewith, an oscillatory driving armature for the main magnet, a switching armature for the supplemental magnet adapted to open'and close the circuit through the magnets, a time train driving wheel, a pawl engaging said wheel, a spring arranged to cause the pawl to drive said wheel, and means oscillated with the driving armature for tensioning the driving spring and retracting the pawl, said means also adapted to engage and move said switching armature of the supplemental magnet.

4. A time train driving mechanism comprising a main driving magnet, a supplemental switching magnet in series therewith, a driving armature for the main magnet, a. conducting spring finger bearing an armature for the supplemental magnet and a contact adapted to open and close the circuit through the magnets, a time train driving wheel, a pawl engaging said wheel, a spring arranged to cause the pawlto drive said wheel, and means actuated b the movements of the driving armature or tensioning the driving spring and retracting the pawl, said means also adapted to engage and move said spring finger.

.5. A time train driving mechanism comprising a main driving magnet, a ,su plemental switching magnet in series therewith, an oscillatory driving armature for 6. A ti me train driving mechanism com prising a main driving magnet, .a supplemental switching magnet in series therewith,

an oscillatory driving armature tor the main magnet, a rocker connected to and oscillating with said armature, a switching armature for the supplemental magnet adapted to open and close the circuit through the magnets, a time train driving wheel, a pawl carried by said rocker and engaging said wheel, a spring connected to and tensioned to cause the pawl to drive said wheel, and a fork on said rocker adapted to engage and move said switching armature of the supplemental magnet. d i

7. A time train driving mechanism comprising a main driving magnet, a supplemental switching magnet in series therewith, an oscillatory driving armature for the main magnet, a rocker connected to and oscillating' with said armature, a switching armature for the supplemental magnet adapted to open and close the circuit through thema-gnets, a time train driving wheel, a pawl carried by said rocker and engaging said wheel, a spring connected to and tensioned to cause the pawl to drive said wheel, a fork on said rocker, adapted to engage and move said switching armature of the supplemental magnet, and means for limiting the oscillatory movements of the driving armature.

8. A time train driving mechanism comprising a supporting plate,a driving magnet, a switching magnet in series therew1th,a n

meaeao oscillatory armature for the driving magnet,

a rocker connected to and oscillating with said armature, an armature for the switching magnet adapted to open and close the circuit through the magnets, a time train driving wheel, a pawl carried by said rocker and engaging said wheel, a spring connected to and tensioned to cause the pawl to drive said wheel, and a fork on said rocker adapted to engage and move the armature of the switching magnet, said fork extending through a slot in the supporting plate and engaging the walls thereof for limiting its 'movement and the movement of the driving between said wheel and spring, and a rocker actuated by the movements of the driving arm'atune for tensioning the driving spring and retracting the pawl, said rocker also engaging and moving the switching armature.

10. A time train driving mechanism comprising a main driving magnet, an oscillatory armature for said magnet, a drivin spring, means actuated by the oscillations 0 said armature for tensioning the driving spring, a supplemental switching magnet in series with the main magnet, a switching armature for the supplemental magnet, and means actuated by the oscillations of the. driving armature adapted to engage and cause the switching armature to open and close the circuit through the magnets.

NEWTON D. HOLBROOK. 

